Memory reduction device of stereoscopic image display for compensating crosstalk

ABSTRACT

A memory reduction device of a stereoscopic image display includes a compression unit configured to receive first to fourth input data belonging to Gn and comprised of K1 bit, respectively, align the first to fourth input data in order of a data size to generate first to fourth alignment data, generate first to fourth compression data groups including first and second compression data having K2 bits smaller than K1 bits and third compression data having K3 bits smaller than K2 bits based on the first to fourth alignment data, derive an outlier from the first to fourth input data by using a deviation between the first to fourth alignment data, select any one of the first to fourth compression data groups, as the compressed Gn−1 according to the presence or absence of the outlier and an outlier derivation position.

This nonprovisional application claims priority under 35 U.S.C. §119(a)on Patent Application No. 10-2012-0101164 filed in Republic of Korea onSep. 12, 2012, the entire contents of which are hereby incorporated byreference.

BACKGROUND

1. Field

This document relates to a memory reduction device of a stereoscopicimage display for compensating for crosstalk.

2. Related Art

A stereoscopic image display implements a stereoscopic image, i.e., athree-dimensional (3D) image, by using a stereoscopic technique or anautostereoscopic technique. The stereoscopic technique, which usesparallax images of left and right eyes having great stereoscopic effect,includes glass type stereoscopic scheme and a non-glass typestereoscopic technique, both of which have been commercialized.

A glass type stereoscopic image display is divided into a polarizationglass type stereoscopic image display and a shutter-glass typestereoscopic image display. The polarization glass type stereoscopicimage display includes a polarization splitter, such as a patternedretarder, joined to a display panel. The patterned retarder splitspolarized light of a left eye image and a right eye image displayed onthe display panel. When enjoying (or viewing) a stereoscopic imagethrough a polarization glass type stereoscopic image display, a viewer(or a user) wears polarization glasses to view polarized light of a lefteye image through a left eye filter of the polarization glasses andpolarized light of a right eye image through a right eye filter of thepolarization glasses, obtaining a three-dimensional (3D) effect.

The shutter-glass type stereoscopic image display, without apolarization splitter attached to a display panel, alternately displaysa left eye image and a right eye image on the display panel and opens aleft eye shutter of shutter glasses such that it is synchronized withthe left eye image and opens right eye shutter of the shutter glassessuch that it is synchronized with the right eye image. When viewing astereoscopic image through the shutter-glass type stereoscopic imagedisplay, a viewer wears shutter glasses to view polarized light of aleft eye image through the left eye shutter of the shutter glasses andpolarized light of a right eye image through the right eye shutter ofthe shutter glasses, obtaining a 3D effect.

Picture quality evaluation items of a stereoscopic image display includecontrast, flicker, 3D crosstalk, and the like, and among them, 3Dcrosstalk is the biggest issue. 3D crosstalk is a phenomenon by whichlight (light leakage) of anther eye image is made incident to one eye(right eye or left eye) of a viewer to distort luminance of the one eyeimage. 3D crosstalk is severely appears in the shutter-glass typestereoscopic image display in which left eye images and right eye imagesare alternately displayed at certain timer intervals, but it is alsoproblematic even with the polarization glass type stereoscopic imagedisplay in which left eye images and right eye images are simultaneouslydisplayed separately by the line.

Recently, in order to compensate for 3D crosstalk, a technique ofpredicting a portion in which crosstalk is generated by comparing lefteye and right eye images displayed to neighbor to each other temporally(or spatially), and modulating data of the predicted portion with acompensation value has been proposed by the applicant of thisapplication. As illustrated in FIG. 1, this technique compensates for 3Dcrosstalk by using a crosstalk compensation unit 1 comparing Gn−1 to bedisplayed to neighbor to each other temporally (or spatially) andmodulating Gn into Gn′ and a memory 2 storing Gn−1 for a certain periodof time. Gn, any one of left eye data and right eye data, indicatesframe (or line) data to be displayed in nth frame (or nth horizontalpixel line), and Gn−1, the other of the left eye data and the right eyedata, indicates frame (or line) data to be displayed in (n−1)th frame(or (n−1)th horizontal pixel line). The crosstalk compensation unit 1 isimplemented as a look-up table from which the compensation value Gn′ isread by using Gn and Gn−1 as read addresses.

In this case, however, in order to implement a 3D crosstalk compensationtechnique, a large capacity memory is required. When red data (R), greendata (GL), and blue data (GL) for image implantation are comprised of 8bits, respectively, an existing 3D crosstalk compensation techniquerequires a memory having a capacity of about (horizontalresolution*3*8*2) bits although it is applied to a polarization glasstype. For example, in case of applying the existing 3D crosstalkcompensation technique to a polarization glass-type stereoscopic imagedisplay implementing FHD resolution, a required capacity of a memoryamounts to (1920*3*8*2=92160 bit)(=11.25 KByte). When the existing 3Dcrosstalk compensation technique is applied to the shutter-glass typestereoscopic image display, a required capacity of a memory is furtherincreased.

SUMMARY

An aspect of the present invention provides a memory reduction device ofa stereoscopic image display capable of reducing a capacity of a memoryrequired for compensating for 3D crosstalk.

In an aspect, a memory reduction device of a stereoscopic image displayfor compensating for 3D crosstalk by comparing Gn and Gn−1 to bedisplayed to neighbor to each other and modulating Gn into Gn′,comprises: a memory; and a compression unit configured to receive firstto fourth input data belonging to Gn and comprised of K1 bit,respectively, align the first to fourth input data in order of a datasize to generate first to fourth alignment data, generate first tofourth compression data groups including first and second compressiondata having K2 bits smaller than the K1 bits and third compression datahaving K3 bits smaller than the K2 bits based on the first to fourthalignment data, derive an outlier from the first to fourth input data byusing a deviation between the first to fourth alignment data, select anyone of the first to fourth compression data groups, as a compressed Gn−1according to the presence or absence of the outlier and an outlierderivation position, and store the same in the memory.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompany drawings, which are included to provide a furtherunderstanding of the invention and are incorporated on and constitute apart of this specification illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a view schematically illustrating an existing 3D crosstalkcompensation technique.

FIG. 2 is a block diagram of a stereoscopic image display according toan embodiment of the present invention.

FIG. 3 is a detailed view illustrating an operation of a display panel,a pattered retarder, and polarization glasses when the stereoscopicimage display of FIG. 2 is implemented as a polarization glass typestereoscopic image display.

FIG. 4 is a detailed view illustrating an operation of the display paneland shutter glasses when the stereoscopic image display of FIG. 2 isimplemented as a shutter-glass type stereoscopic image display.

FIG. 5 is a view illustrating a data modulation circuit illustrated inFIG. 2.

FIG. 6 is a view illustrating a capacity of data before and aftercompression.

FIG. 7 is a view illustrating a capacity of data before and afterrestoration.

FIG. 8 is a view illustrating a detailed configuration of a compressionunit of FIG. 5.

FIG. 9 is a view illustrating an operation of an aligning unit of FIG.8.

FIGS. 10 to 13 are views illustrating respective operations of first tofourth group generating units of FIG. 8.

FIG. 14 is a view illustrating an operation of a deviation driving unitof FIG. 8.

FIG. 15 is a view illustrating an operation of a select signalgenerating unit of FIG. 8.

FIG. 16 is a view illustrating an operation of a restoration unit ofFIG. 5.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings. Throughout the specification, the likereference numerals denote the substantially same elements. In describingthe present invention, if a detailed explanation for a related knownfunction or construction is considered to unnecessarily divert the gistof the present invention, such explanation will be omitted but would beunderstood by those skilled in the art. Names of elements used in thefollowing description are selected for the description purpose and maybe different from those of actual products.

A memory reduction device of a stereoscopic image display according toan embodiment of the present invention may be applied to every scheme ofcompensating for 3D crosstalk by utilizing a memory in a stereoscopicimage display expressing a stereoscopic image by splitting a left eyeimage and a right eye image through space division or time division. Inthe embodiment with respect to the memory reduction device of astereoscopic image display according to the present invention, a glasstype stereoscopic image display will be described as an example, but thepresent invention may also be applicable to a non-glass typestereoscopic image display that compensates for 3D crosstalk byutilizing a memory, without a great modification. Thus, it should beappreciated that the memory reduction device of a stereoscopic imagedisplay according to an embodiment of the present invention is notlimited to a glass type stereoscopic image display. A glass typestereoscopic display device is classified into a polarization-glass typestereoscopic image display as illustrated in FIG. 3 and a shutter-glasstype stereoscopic image display as illustrated in FIG. 4.

FIG. 2 is a block diagram of a stereoscopic image display according toan embodiment of the present invention. FIG. 3 is a detailed viewillustrating an operation of a display panel, a pattered retarder, andpolarization glasses when the stereoscopic image display of FIG. 2 isimplemented as a polarization glass type stereoscopic image display.FIG. 4 is a detailed view illustrating an operation of the display paneland shutter glasses when the stereoscopic image display of FIG. 2 isimplemented as a shutter-glass type stereoscopic image display.

In the embodiment described hereinafter, a stereoscopic image displayimplemented as a liquid crystal display (LCD) will be largely described,but it should be appreciated that the technical concept of the presentinvention is not limited thereto. The stereoscopic image displayaccording to an embodiment of the present invention may be implementedas a flat panel display (FPD) such as a liquid crystal display (LCD), afield emission display (FED), a plasma display panel (PDP), an organiclight emitting diode (OLED), or the like.

Referring to FIG. 2, the stereoscopic image display according to anembodiment of the present invention includes a display panel 10, a gatedriving circuit 11, a data driving circuit 12, a timing controller 13, adata modulation circuit 14, a host system 15, and the like.

The display panel 10 includes an upper substrate and a lower substratefacing with a liquid crystal layer interposed therebetween. A pixelarray including liquid crystal cells arranged in a matrix form by acrossing structure of data lines DL and gate lines GL (or scan lines) isformed on the display panel 10. The liquid crystal cells of the pixelarray display an image by adjusting a transmission amount of light bydriving liquid crystal of the liquid crystal layer by a voltagedifference between a pixel electrode in which a data voltage is chargedand a common electrode to which a common voltage is applied through theTFTs, respectively.

Black matrices and color filters are formed on an upper substrate of thedisplay panel 10. In case of a vertical electric field driving method(or a vertical field switching mode) such as a twisted nematic (TN) modeor a vertical alignment (VA) mode, the common electrode is formed on theupper substrate, and in case of a horizontal electric field drivingmethod such as an in-plane switching (IPS) mode or a fringe fieldswitching (FFS) mode, the common electrode is formed together with thepixel electrode on the lower substrate. A liquid crystal mode of thedisplay panel 10 may be implemented as any liquid crystal mode, as wellas as the TN mode, the VA mode, the IPS mode, or the FFS mode. Thedisplay panel 10 may be implemented in any form of a transmissive liquidcrystal display panel, a transflective liquid crystal display panel, areflective liquid crystal display panel, or the like. The transmissiveliquid crystal display panel and the transflective liquid crystaldisplay panel require a backlight unit. A backlight unit may beimplemented as a direct type backlight unit or an edge type backlightunit. An upper polarization film is attached to the upper substrate ofthe display panel 10, and a lower polarization film is attached to thelower substrate of the display panel 10. An alignment film for setting apre-tilt angle of liquid crystal is formed on the upper substrate andthe lower substrate. A spacer for maintaining a cell gap of the liquidcrystal is formed between the upper substrate and the lower substrate ofthe display panel 10.

The gate driving circuit 11 sequentially supplies gate pulses to thegate lines GL of the display panel 10 under the control of the timingcontroller 13. The data driving circuit 12 converts 2D video data RGB2Dor modulated 3D video data RGB3D′ into a positive polarity/negativepolarity gamma compensation voltage to generate positivepolarity/negative polarity analog data voltages under the control of thetiming controller 13. The positive polarity/negative polarity analogdata voltages output from the data driving circuit 12 are supplied tothe data lines DL of the display panel 10.

The timing controller 13 receives the 2D video data RGB2D or 3D videodata RGB3D′ modulated for crosstalk compensation, timing signals, a modesignal MODE, and the like, from the data modulation circuit 14. Thetiming signals include a vertical synchronization signal, a horizontalsynchronization signal, a data enable signal, a clock signal, and thelike. The mode signal MODE is a signal indicating a 2D mode or a 3Dmode. Based on the 2D video data RGB2D or the modulated 3D image dataRGB3D′, the timing signals, and the mode signal MODE, the timingcontroller 13 generates a gate control signal GCS for controlling thegate driving circuit 11 and a data control signal DCS for controllingthe data driving circuit 12. The timing controller 13 supplies the gatecontrol signal GCS to the gate driving circuit 11. The timing controller13 supplies the 2D video data RGB2D or the modulated 3D video dataRGB3D′ and the data control signal DCS to the data driving circuit 12.

The host system 15 may be implemented in the form of a system on chip(SoC) including a scaler for converting the 2D video data RGB2D or the3D video data RGB3D input from an external video source device into adata format appropriate for resolution of the display panel 10. Also,the host system 15 may include a 3D formatter for converting 3D videodata RGB3D into a 3D format fitting a time division scheme or a spacedivision scheme in a 3D mode. The host system 15 supplies 2D video dataRGB2D or 3D video data RGB3D to the data modulation circuit 14 throughan interface such as a low voltage differential scaling (LVDS)interface, a transition minimized differential signaling (TMDS)interface, or the like. Also, the host system 15 supplies the timingsignals, the mode signal MOD, and the like, to the data modulationcircuit 14.

The data modulation circuit 14 bypasses the 2D video data RGB2D to thetiming controller 13 in a 2D mode, rather than modulating it. The datamodulation circuit 14 receives the 3D video data RGB3D in the 3D mode.The data modulation circuit 14 predicts a portion having 3D crosstalk bycomparing a left eye image and a right eye image displayed to beadjacent temporally (or spatially), and modulates data of the predictedportion with a compensation value, and outputs the modulated 3D videodata RGB3D′. The data modulation circuit 14, including a memory forstoring the 3D video data RGB3D for a certain period of time and acompression unit and a restoration unit for reducing a capacity of thememory, significantly reduces the capacity of the memory required for 3Dcrosstalk compensation. A memory reduction device belonging to the datamodulation circuit 14 will be described in detail with reference toFIGS. 5 to 16 later.

When the stereoscopic image display of FIG. 2 is implemented as apolarization glass type stereoscopic image display, the stereoscopicimage display further includes a patterned retarder 103 and polarizationglasses 20 as illustrated in FIG. 3. The display panel 10 displays aleft eye image L (or a right eye image) in odd-number horizontal pixellines and displays a right eye image R (or a left eye image) ineven-number horizontal pixel lines. An image displayed in the pixels ofthe display panel 10 is made incident to the patterned retarder 103disposed on the display panel 10 through an upper polarization film 101

The patterned retarder 103 includes a first retarder pattern facing theodd-number horizontal pixel lines and a second retarder pattern facingthe even-number horizontal pixel lines. The first retarder patternconverts light made incident from the display panel 10 into firstcircular polarization (left circular polarization). The second retarderpattern converts light made incident from the display panel 10 intosecond circular polarization (right circular polarization). Thepolarization glasses 20 includes a left eye polarization filter allowingthe first circular polarization converted by the first retarder patternto pass therethrough and a right eye polarization filter allowing thesecond circular polarization converted by the second retarder pattern topass therethrough. For example, the left eye polarization filter maymake left circular polarization pass therethrough and the right eyepolarization filter may make right circular polarization passtherethrough.

When the polarization glass type stereoscopic image display operates inthe 3D mode, the left eye image L displayed in the odd-number horizontalpixel lines of the display panel 10 is converted into first circularpolarization by the first retarder pattern and the right eye image Rdisplayed in the even-number horizontal pixel lines of the display panel10 is converted into second circular polarization by the second retarderpattern. The first circular polarization reaches the user's left eye,after passing through the left eye polarization filter of thepolarization glasses 20, and the second circular polarization reachesthe user's right eye, after passing through the right eye polarizationfilter. Thus, the user views only the left eye image L through his lefteye and only the right eye image R through his right eye, obtaining athree-dimensional (3D) effect from binocular disparity.

When the stereoscopic image display of FIG. 2 is implemented as ashutter-glass type stereoscopic image display, the stereoscopic imagedisplay further includes shutter glasses 30 as illustrated in FIG. 4.

The host system 15 may output a shutter control signal to open and closea left eye shutter and a right eye shutter of the shutter glasses 30.The shutter control signal is transmitted to a shutter control signalreception unit through a wired/wireless interface. The shutter controlsignal reception unit may be installed in the shutter glasses 30 or maybe fabricated as a separate module and detachably attached to theshutter glasses 30.

The shutter glasses 30 include a left eye shutter and a right eyeshutter which are electrically separately controlled. The left eyeshutter and the right eye shutter include a birefringent medium foradjusting light transmittance to transmit and block light. The left eyeshutter and the right eye shutter may include a first transparentsubstrate, a first transparent electrode formed on the first transparentsubstrate, a second transparent substrate, a second transparentelectrode formed on the second transparent substrate, and a liquidcrystal layer interposed between the first and second transparentsubstrates, respectively. A reference voltage is supplied to the firsttransparent electrode, and an ON/OFF voltage is supplied to the secondtransparent electrode. When the ON voltage is applied to the secondtransparent electrode, the left eye shutter and the right eye shuttertransmit incident light to a viewer's eyes, and when the OFF voltage isapplied to the second transparent electrode, the left eye shutter andthe right eye shutter block light transmission to the viewer's eyes.

When the shutter glass type stereoscopic image display operates in the3D mode, the left eye image L and the right eye image R are alternatelydisplayed on the display panel 10 at certain time intervals (e.g.,frames) as illustrated in FIG. 4. The shutter glasses 30 open only theleft eye shutter during nth frame period (Nth FR.) in which the left eyeimage L is displayed on the display panel 10, and open only the righteye shutter during (n+)th frame period ((N+1)th FR.) in which the righteye image R is displayed on the display panel 10. Thus, the user viewsonly the left eye image L through his left eye and only the right eyeimage R through his right eye, obtaining a three-dimensional (3D) effectfrom binocular disparity.

FIG. 5 is a view illustrating a data modulation circuit illustrated inFIG. 2. FIG. 6 is a view illustrating a capacity of data before andafter compression. FIG. 7 is a view illustrating a capacity of databefore and after restoration.

Referring to FIG. 5, the data modulation circuit 14 compensates for 3Dcrosstalk by using a crosstalk compensation unit 144 for comparing Gnand Gn−1 to be displayed to be adjacent temporally (or spatially) andmodulating Gn into Gn′ and a memory 142 storing Gn−1 for a certainperiod of time. Gn is any one of left eye data and right eye data,indicating frame (or line) data of a 3D I mage to be displayed in nthframe (or nth horizontal pixel line) and Gn−1 is the other of the lefteye data and the right eye data, indicating frame (or line) data of a 3Dimage to be displayed in (n−1)th frame (or (n−1)th horizontal pixelline). The crosstalk compensation unit 144 may include a look-up tablefor reading a compensation value Gn′ by using Gn and Gn−1 as readaddresses and outputting a modulated 3D video data RFG3D′.

The crosstalk compensation unit 144 has the substantially same functionas that of data modulation units respectively disclosed in Korean PatentApplication No. 10-2012-0047716 (May 4, 2012), Korean Patent ApplicationNo. 10-2011-0067467 (Jul. 7, 2011), and Korean Patent Application No.10-2010-0125622 (Dec. 10, 2010) filed by the applicant of the presentinvention. Also, the crosstalk compensation unit 144 may be replaced bya viewing angle compensation circuit disclosed in Korean PatentApplication No. 10-2011-0080600 (Aug. 12, 2011) filed by the applicantof the present invention.

The data modulation circuit 14 includes a compression unit 141 forcompressing data to be stored in the memory 142 to reduce a capacity ofthe memory 142. The compression data stored in the memory 142 isrestored to have the original size through a restoration unit 143. InFIG. 5, a memory reduction device 140 includes only the compression unit141 and the memory 142 in a narrow sense and includes up to therestoration unit 143 in a broad sense.

The compression unit 141 receives first to fourth input data X1˜X4belonging to Gn and comprised of K1 bits, respectively. The compressionunit 141 aligns the first to fourth data X1˜X4 in order of a data sizeto generate first to fourth alignment data, and subsequently generatesfour compression data groups. Each of the four compression data groupsinclude first and second compression data (Y1 and Y2) having K2 bitssmaller than K1 bits and third compression data F having K3 bits smallerthan K2 bits based on the first to fourth alignment data as illustratedin FIG. 6. Thereafter, the compression unit 141 derives an outlier fromthe first to fourth input data X1˜X4 by using a deviation between thefirst to fourth alignment data, and supplies any one of the fourcompression data groups according to the presence or absence of theoutlier and an outlier derivation position to the memory 142. Here, theoutlier is defined as data having a value different by more than apredetermined value based on an average value of the first to fourthalignment data. The outlier may be determined at least one of the firstto fourth alignment data. As illustrated in FIG. 6, the capacity of thecompression data groups Y1, Y2, and F stored in the memory 142 issignificantly reduced relative to the total capacity of the first tofourth input data X1˜X4.

The number of bits of the third compression data F is set to be equal tothe number of (i.e., four) input data considered for compression. Thethird compression data F indicates the presence and absence of anoutlier and a position of data corresponding to the outlier. When thereis no outlier in the first to fourth input data X1˜X4, the mostsignificant K2 bits of the average value of the first to fourth inputdata X1˜X4 are allocated to the first compression data Y1, leastsignificant (K1-K2) bits of the average value of the first to fourthinput data X1˜X4 are allocated to least significant bits of the secondcompression data Y2, and 0 indicating that there is no outlier in everybit is allocated to the third compression data F. When there is anoutlier in the first to fourth input data X1˜X4, an average value ofinput data, excluding the outlier, among the first to fourth input dataX1˜X4 is allocated to the first compression data Y1, an average value ofinput data corresponding to the outlier is allocated to the secondcompression data Y2, and ‘1’ is allocated to the third compression dataF according to a position of the outlier, and 0 is allocated to thethird compression data F according to a position of a non-outlier.

The restoration unit 143 receives the compression data groups Y1, Y2,and F. The restoration unit 143 restores the compression data groups Y1,Y2, and F into the first to fourth restoration data X1′˜X4′ comprised ofK1 bits, respectively, according to the presence and absence of anoutlier and an outlier derivation position. The restoration unit 143supplies the first to fourth restoration data X1′˜X4′ belonging to Gn−1to the crosstalk compensation unit 144. The first to fourth restorationdata X1′˜X4′ are slightly different from the first to fourth input dataX1˜X4. In case of 3D crosstalk compensation, importance of leastsignificant bits and importance of edge information do not have muchimportance, so a lossy compression and lossy restoration count little ornothing.

In the following description of an embodiment of the present invention,it is assumed that first to fourth input data X1˜X$ and first to fourthrestoration data X1′˜X4′ have 8 bits, first and second compression datahave 6 bits, and third compression data has 4 bits. In this case, whenthe 3D crosstalk compensation technique is applied to the polarizationglass type stereoscopic image display implementing FHD resolution, arequired capacity of a memory is 5.625 Kbyte, equivalent to 50% of theexisting capacity (11.25 Kbyte) of the memory.

FIG. 8 is a view illustrating a detailed configuration of a compressionunit of FIG. 5. FIG. 9 is a view illustrating an operation of analigning unit of FIG. 8. FIGS. 10 to 13 are views illustratingrespective operations of first to fourth group generating units of FIG.8. FIG. 14 is a view illustrating an operation of a deviation drivingunit of FIG. 8. FIG. 15 is a view illustrating an operation of a selectsignal generating unit of FIG. 8. In the following description, 2′b00,2′b01, 2′b10, 2′b11 represent binary numbers ‘00’, ‘01’, ‘10’, ‘11’comprised of 2 bits, respectively, and 4′b0000, 4′b0010, 4′b0100,4′b1000 represent ‘0001’, ‘0010’, ‘0100’, ‘1000’ comprised of 4 bits,respectively. And, [a:b] represents a number of data bits from a-th bitto b-th bit (b<a).

Referring to FIG. 8, the compression unit 141 includes an aligning unit141A, first to fourth group generating units 141B, 141C, 141D, and 141E,a deviation deriving unit 141F, a select signal generating unit 141G,and a selecting unit 141H.

As illustrated in FIG. 9, the aligning unit 141A adds binary numbers‘00’, ‘01’, ‘10’, ‘11’ comprised of 2 bits to the 8-bit first to fourthinput data X1˜X4, respectively, to generate 10-bit x[1],x[2],x[3],x[4].x[1],x[2],x[3],x[4] include original position information together withdata values of the first to fourth input data X1˜X4, respectively. Thealigning unit 141A sorts x[1],x[2],x[3],x[4] in order of a data size byusing a known sorting algorithm such as selection soft, bubble sort,insertion sort, and the like, to generate 10-bit first to fourth sortdata A, B, C, and D. The first to fourth alignment data are aligned inorder of A≧B≧C≧D.

The first group generating unit 141B generates a first compression datagroup GC#1 including 6-bit first compression data Y1, 6-bit secondcompression data Y2, and 4-bit third compression data F based on the10-bit first to fourth alignment data A, B, C, and D as illustrated inFIG. 10. The first compression data group GC#1 corresponds to a datagroup in which an outlier does not exist. The first group generatingunit 141B generates 8-bit first to fourth corrected alignment data A′,B′, C′, and D′ excluding least significant 2 bits in the 10-bit first tofourth alignment data A, B, C, and D. Here, the 8-bit first to fourthcorrected alignment data A′, B′, C′, and D′ individually correspond toany one of the 8-bit first to fourth input data X1˜X4, respectively. Thefirst group generating unit 141B averages the 8-bit first to fourthcorrected alignment data A′, B′, C′, and D′ to calculate 8-bit firstaverage data M1. The first group generating unit 141B allocates mostsignificant 6 bits M1[7:2] of the 8-bit first average data M1 to thefirst compression data Y1. The first group generating unit 141Ballocates least significant 2 bits M1[1:0] of the 8-bit first averagedata M1 to least significant 2 bits of the second compression data Y2,and fills upper 4 bits of the second compression data Y2 with ‘0000’.The first group generating unit 141B allocates ‘0000’ to the 4-bit thirdcompression data F.

As illustrated in FIG. 11, the second group generating unit 141Cgenerates a second compression data group GC#2 including 6-bit firstcompression data Y1, 6-bit second compression data Y2, and 4-bit thirdcompression data F based on the 10-bit first to fourth alignment data A,B, C, and D. The second compression data group GC#2 corresponds to adata group in which an outlier exists in a first position (e.g., when Dis an outlier). The second group generating unit 141C generates 8-bitfirst to fourth corrected alignment data A′, B′, C′, and D′ excludingleast significant 2 bits in the 10-bit first to fourth alignment data A,B, C, and D. The second group generating unit 141C averages the 8-bitfirst to third corrected alignment data A′, B′, and C′ to calculate8-bit second average data M2. The second group generating unit 141Callocates most significant 6 bits M1[7:2] of the 8-bit second averagedata M2 to the first compression data Y1. The second group generatingunit 141C allocates most significant 6 bits D′[7:2] of the 8-bit fourthcorrected alignment data D′ to the second compression data Y2. Also, thesecond group generating unit 141C allocates any one of ‘0001’, ‘0010’,‘0100’, and ‘1000’ to the 4-bit third compression data F according towhich of the first to fourth input data X1˜X4 the 8-bit fourth correctedalignment data D′ corresponds to. The second group generating unit 141Cmay know which of the first to fourth input data X1˜X4 the fourthcorrected alignment data D′ corresponds to according to positioninformation D″ indicated in the least significant 2 bits D[1:0] of thefourth alignment data D.

As illustrated in FIG. 12, the third group generating unit 141Dgenerates a third compression data group GC#3 including 6-bit firstcompression data Y1, 6-bit second compression data Y2, and 4-bit thirdcompression data F based on the 10-bit first to fourth alignment data A,B, C, and D. The third compression data group GC#3 corresponds to a datagroup in which an outlier exists in a second position (e.g., when A andB are outliers). The third group generating unit 141D generates 8-bitfirst to fourth corrected alignment data A′, B′, C′, and D′ excludingleast significant 2 bits in the 10-bit first to fourth alignment data A,B, C, and D. The third group generating unit 141D averages the 8-bitthird and fourth corrected alignment data C′ and D′ to calculate 8-bit3a-th average data M3a and subsequently allocates most significant 6bits M3a[7:2] of the 8-bit 3a-th average data M3a to the firstcompression data Y1. The third group generating unit 141D averages the8-bit first and second corrected alignment data A′ and B′ to calculate8-bit 3b-th average data M3b and subsequently allocates most significant6 bits M3b[7:2] of the 8-bit 3b-th average data M3b to the secondcompression data Y2. The third group generating unit 141D selectsmutually different two (Fa and Fb) from among ‘0001’, ‘0010’, ‘0100’,and ‘1000’ according to which of the 8-bit first to fourth input dataX1˜X4 the 8-bit first and second corrected alignment data A′ and B′individually correspond to, adds up the selected two (Fa and Fb), andallocates the same to the 4-bit third compression data F. The thirdgroup generating unit 141D may know which of the first to fourth inputdata X1˜X4 the first corrected alignment data A′ corresponds toaccording to position information A″ indicated in the least significant2 bits A[1:0] of the first alignment data A, and also know which of thefirst to fourth input data X1˜X4 the second corrected alignment data B′corresponds to according to position information B″ indicated in theleast significant 2 bits B[1:0] of the second alignment data B.

As illustrated in FIG. 13, the fourth group generating unit 141Egenerates a fourth compression data group GC#4 including 6-bit firstcompression data Y1, 6-bit second compression data Y2, and 4-bit thirdcompression data F based on the 10-bit first to fourth alignment data A,B, C, and D. The fourth compression data group GC#4 corresponds to adata group in which an outlier exists in a third position (e.g., when Ais an outlier). The fourth group generating unit 141E generates 8-bitfirst to fourth corrected alignment data A′, B′, C′, and D′ excludingleast significant 2 bits in the 10-bit first to fourth alignment data A,B, C, and D. The fourth group generating unit 141E averages the 8-bitsecond to fourth corrected alignment data B′, C′, and D′ to calculate8-bit fourth average data M4. The fourth group generating unit 141Eallocates most significant 6 bits M4[7:2] of the 8-bit fourth averagedata M4 to the first compression data Y1. The fourth group generatingunit 141E allocates most significant 6 bits A′[7:2] of the 8-bit firstcorrected alignment data A′ to the second compression data Y2. Thefourth group generating unit 141E allocates any one of ‘0001’, ‘0010’,‘0100’, and ‘1000’ to the third compression data F according to which ofthe 8-bit first to fourth input data X1˜X4 the 8-bit first correctedalignment data A′ corresponds to. The fourth group generating unit 141Emay know which of the first to fourth input data X1˜X4 the firstcorrected alignment data A′ corresponds to according to positioninformation A″ indicated in the least significant 2 bits A[1:0] of thefirst alignment data A.

The deviation deriving unit 141F calculates a maximum deviation Dt andfirst to third deviations D1, D2, and D3 through arithmetic operationwith respect to the first to fourth 10-bit alignment data A, B, C, and Das illustrated in FIG. 14. The maximum deviation Dt is a deviationbetween the first and fourth alignment data A and D, the first deviationD1 is a deviation (C-D) between the third and fourth alignment data Cand D, the second deviation D2 is a deviation (B-C) between the secondand third alignment data B and C, and the third deviation D3 is adeviation (A-B) between the first and second alignment data A and B.

As illustrated in FIG. 15, the select signal generating unit 141Gderives an outlier from the first to fourth alignment data A, B, C, andD by using deviations Dt and D1 to D3 supplied from the deviationderiving unit 141F, and outputs a different select signal SEL accordingto the presence and absence of an outlier and an outlier derivationposition. When the maximum deviation Dt is smaller than a predeterminedthreshold value, the select signal generating unit 141G determines thatthere is no outlier, and outputs a select signal ‘00’. When the firstdeviation D1 among the first to third deviations D1, D2, and D3 is thegreatest in a state in which the maximum deviation Dt is greater thanthe predetermined threshold value, the select signal generating unit141G determines that the fourth alignment data D is an outlier, andoutputs a select signal ‘01’. When the second deviation D2 among thefirst to third deviations D1, D2, and D3 is the greatest in a state inwhich the maximum deviation Dt is greater than the predeterminedthreshold value, the select signal generating unit 141G determines thatthe first and second alignment data A and B are outliers (or maydetermined that the third and fourth alignment data C and D areoutliers), and outputs a select signal ‘10’. When the third deviation D3among the first to third deviations D1, D2, and D3 is the greatest in astate in which the maximum deviation Dt is greater than thepredetermined threshold value, the select signal generating unit 141Gdetermines that the first alignment data A is an outlier, and outputs aselect signal ‘11’.

In response to the select signal ‘00’, the selecting unit 141H storesthe first to third compression data Y1, Y2, and F of the firstcompression data group GC#1 in the memory 142. In response to the selectsignal ‘01’, the selecting unit 141H stores the first to thirdcompression data Y1, Y2, and F of the second compression data group GC#2in the memory 142. In response to the selected signal ‘10’, theselecting unit 141H stores the first to third compression data Y1, y2,and F of the third compression data group GC#3 in the memory 142. Inresponse to the select signal ‘11’, the selecting unit 141H stores thefirst to third compression data Y1, Y2, and F of the fourth compressiondata group GC#4 in the memory 142.

FIG. 16 is a view illustrating an operation of the restoration unit 143of FIG. 5.

Referring to FIG. 16, the restoration unit 143 restores the 6-bit firstand second compression data Y1 and 2 and the 4-bit third compressiondata F stored in the memory 142 into 8-bit first to fourth restorationdata X1′˜X4′ differently according to the presence and absence of anoutlier and an outlier derivation position.

When the 4-bit third compression data F is ‘0000’, the restoration unit143 determines that there is no outlier, and restores the first tofourth restoration data X1′˜X4′ with the same value. Namely, therestoration unit 143 uniformly allocates the 6-bit first compressiondata Y1 to most significant 6 bits of the 8-bit first to fourthrestoration data X1′˜X4′, respectively, and least significant 2 bits ofthe second compression data Y2 to least significant 2 bits of the 8-bitfirst to fourth restoration data X1′˜X4′, respectively.

When the 4-bit third compression data F is not ‘0000’, the restorationunit 143 determines that there is an outlier, and restores datacorresponding to the position of the outlier in the first to fourthrestoration data X1′˜X4′ to a different value from other data. When the4-bit third compression data F is not ‘0000’, the restoration unit 143fills the most significant 6 bits of each of the 8-bit first to fourthrestoration data X1′˜X4′ with the 6-bit first compression data Y1uniformly, and fills the least significant 2 bits of each of the 8-bitfirst to fourth restoration data X1′˜X4′ with ‘00’ uniformly. In thisstate, the restoration unit 143 determines which bit of the 4-bit thirdcompression data F is ‘1’. F[0] is a flag for deriving the firstrestoration data X1′, which corresponds to the first bit of the 4-bitthird compression data F. F[1] is a flag for deriving the secondrestoration data X2′, which corresponds to the second bit of the 4-bitthird compression data F. F[2] is a flag for deriving the thirdrestoration data X3′, which corresponds to the third bit of the 4-bitthird compression data F. F[3] is a flag for deriving the fourthrestoration data X4′, which corresponds to the fourth bit of the 4-bitthird compression data F. Based on the bit values of the flag bits, therestoration unit 143 substitutes the most significant 6-bit data of therestoration data corresponding to an outlier of the 8-bit first tofourth restoration data X1′˜X4′ with the 6-bit second compression dataY2.

In other words, when F[0] is ‘1’, the restoration unit 143 replaces thefirst restoration data X1′ from the first compression data Y1 to thesecond compression data Y2, and when F[0] is ‘0’, the restoration unit143 maintains the first restoration data X1′ as the first compressiondata Y1. When F[1] is ‘1’, the restoration unit 143 replaces the secondrestoration data X2′ from the first compression data Y1 to the secondcompression data Y2, and when F[1] is ‘0’, the restoration unit 143maintains the second restoration data X2′ as the first compression dataY1. When F[2] is ‘1’, the restoration unit 143 replaces the thirdrestoration data X3′ from the first compression data Y1 to the secondcompression data Y2, and when F[2] is ‘0’, the restoration unit 143maintains the third restoration data X3′ as the first compression dataY1. When F[3] is ‘1’, the restoration unit 143 replaces the fourthrestoration data X4′ from the first compression data Y1 to the secondcompression data Y2, and when F[3] is ‘0’, the restoration unit 143maintains the fourth restoration data X4′ as the first compression dataY1.

As described above, in the memory reduction device of a stereoscopicimage display according to embodiments of the present invention, sincevideo data required for compensating for 3D crosstalk is compressed inadvance and stored in the memory, a capacity of the memory required forcrosstalk compensation can be drastically reduced.

While the present invention has been shown and described in connectionwith the embodiments, it will be apparent to those skilled in the artthat modifications and variations can be made without departing from thespirit and scope of the invention as defined by the appended claims.

What is claimed is:
 1. A memory reduction device of a stereoscopic imagedisplay for compensating for 3D crosstalk by comparing Gn and Gn−1 to bedisplayed to be adjacent to each other and modulating Gn into Gn′, thememory reduction device comprising: a memory; and a compression unitconfigured to receive first to fourth input data belonging to Gn andcomprised of K1 bits, respectively, align the first to fourth input datain order of a data size to generate first to fourth alignment data,generate first to fourth compression data groups including first andsecond compression data having K2 bits smaller than the K1 bits andthird compression data having K3 bits smaller than the K2 bits based onthe first to fourth alignment data, derive an outlier from the first tofourth input data by using a deviation between the first to fourthalignment data, select any one of the first to fourth compression datagroups, as a compressed Gn−1 according to the presence or absence of theoutlier and an outlier derivation position, and store the same in thememory.
 2. The memory reduction device of claim 1, wherein the thirdcompression data indicates the presence and absence of an outlier and aposition of data corresponding to the outlier, and the number of bits ofthe third compression data is set to correspond to the number of inputdata also considered for compression.
 3. The memory reduction device ofclaim 1, further comprising: a restoration unit configured to receive acompression data group from the memory, and restores the compressiondata group into first to fourth restoration data belonging to the Gn−1and comprised of the K1 bits according to the presence and absence of anoutlier and the outlier derivation position.
 4. The memory reductiondevice of claim 3, wherein the K1 bits are selected as 8 bits, the K2bits are selected as 6 bits, and the K3 bits are selected as 4 bits. 5.The memory reduction device of claim 4, wherein the compressorcomprises: an aligning unit configured to add 2-bit position informationto the 8-bit first to fourth input data and aligning them in order of adata size to generate 10-bit first to fourth alignment data; a firstgroup generating unit configured to generate a first compression datagroup including 6-bit first compression data, 6-bit second compressiondata, and 4-bit third compression data without an outlier based on the10-bit first to fourth alignment data; a second group generating unitconfigured to generate a second compression data group including 6-bitfirst compression data, 6-bit second compression data, and 4-bit thirdcompression data and having an outlier at a first position based on the10-bit first to fourth alignment data; a third group generating unitconfigured to generate a second compression data group including 6-bitfirst compression data, 6-bit second compression data, and 4-bit thirdcompression data and having an outlier at a second position based on the10-bit first to fourth alignment data; and a fourth group generatingunit configured to generate a second compression data group including6-bit first compression data, 6-bit second compression data, and 4-bitthird compression data and having an outlier at a third position basedon the 10-bit first to fourth alignment data.
 6. The memory reductiondevice of claim 5, wherein the first group generating unit averages8-bit first to fourth corrected alignment data obtained by removingleast significant 2 bits from 10-bit first to fourth alignment data tocalculate 8-bit first average data, allocates the most significant 6bits of the 8-bit first average data to the first compression data ofthe first compression data group, allocates the least significant 2 bitsof the 8-bit first average data to least significant 2 bits of thesecond compression data belonging to the first compression data group,and allocates ‘0000’ to most significant 4 bits of second compressiondata belonging to the first compression data group and the 4-bit thirdcompression data belonging to the first compression data group.
 7. Thememory reduction device of claim 5, wherein the second group generatingunit generates 8-bit first to fourth corrected alignment data byremoving least significant 2 bits from the 10-bit first to fourthalignment data, averages the 8-bit first to third corrected alignmentdata to calculate 8-bit second average data, allocates most significant6 bits of the 8-bit second average data to the first compression data ofthe second compression data group, allocates most significant 6 bits ofthe 8-bit fourth corrected alignment data to the second compression dataof the second compression data group, and allocates any one of ‘0001’,‘0010’, ‘0100’, and ‘1000’ to the third compression data of the secondcompression data group according to which of the 8-bit first to fourthinput data the 8-bit fourth corrected alignment data corresponds to. 8.The memory reduction device of claim 5 wherein the third groupgenerating unit generates 8-bit first to fourth corrected alignment databy removing least significant 2 bits from the 10-bit first to fourthalignment data, averages the 8-bit third and fourth corrected alignmentdata to calculate 8-bit 3a-th average data, allocates most significant 6bits of the 8-bit 3a-th average data to the first compression data ofthe third compression data group, averages the 8-bit first and secondcorrected alignment data to calculate 8-bit 3b-th average data,allocates most significant 6 bits of the 8-bit 3b-th average data to thesecond compression data of the third compression data group, selects twodifferent ones among ‘0001’, ‘0010’, ‘0100’, and ‘1000’ according towhich of the 8-bit first to fourth input data the 8-bit first and secondcorrected alignment data corresponds to, and adds the selected twodifferent ones and allocates the sum to the third compression data ofthe third compression data group.
 9. The memory reduction device ofclaim 5, wherein the fourth group generating unit generates 8-bit firstto fourth corrected alignment data by removing least significant 2 bitsfrom the 10-bit first to fourth alignment data, averages the 8-bitsecond to fourth corrected alignment data to calculate 8-bit fourthaverage data, allocates most significant 6 bits of the 8-bit fourthaverage data to the first compression data of the fourth compressiondata group, allocates most significant 6 bits of the 8-bit firstcorrected alignment data to the second compression data of the fourthcompression data group, and allocates any one of ‘0001’, ‘0010’, ‘0100’,and ‘1000’ to the third compression data of the fourth compression datagroup according to which of the 8-bit first to fourth input data the8-bit first corrected alignment data corresponds to.
 10. The memoryreduction device of claim 4, wherein the compression unit comprises: adeviation deriving unit configured to calculate a maximum deviation andfirst to third deviations through arithmetic operation on the 10-bitfirst to fourth alignment data; a select signal generating unitconfigured to derive an outlier from the first to fourth alignment databy using the deviations, and differently output a select signalaccording to the presence and absence of the outlier and the outlierderivation position; and a selecting unit configured to select any oneof the first to fourth compression data groups according to the selectsignal and store the same in the memory.
 11. The memory reduction deviceof claim 10, wherein when the maximum deviation is smaller than apredetermined threshold value, the select signal generating unitdetermines that there is no outlier, and outputs a select signal ‘00’;when the first deviation, among the first to third deviations, is thegreatest in a state in which the maximum deviation is greater than thepredetermined threshold value, the select signal generating unitdetermines that the fourth alignment data is an outlier, and outputs aselect signal ‘01’; when the second deviation, among the first to thirddeviations, is the greatest in a state in which the maximum deviation isgreater than the predetermined threshold value, the select signalgenerating unit determines that the first alignment data and the secondalignment data are outliers, and outputs a select signal ‘10’; and whenthe third deviation, among the first to third deviations, is thegreatest in a state in which the maximum deviation is greater than thepredetermined threshold value, the select signal generating unitdetermines that the first alignment data is an outlier, and outputs aselect signal ‘11’.
 12. The memory reduction device of claim 1, whereinGn is any one of left eye data and right eye data, indicating line dataof a 3D image to be displayed in nth horizontal pixel line, and Gn−1 isthe other of the left eye data and the right eye data, indicating linedata of a 3D image to be displayed in (n−1)th horizontal pixel lineadjacent to the nth horizontal pixel line.